1. Technical Field
This invention relates generally to systems and methods for managing telephone calls within a network. More particularly, the invention relates to a system and method for managing a plurality of calls between two nodes, typically a media gateway and a media gateway controller.
2. History of Related Art
Current telecommunication network architectures include a single node, such as a Mobile Switching Center (MSC), which acts as a combination call gateway and gateway controller. In this single node system, information about the state of telephone calls managed by the node is shared within the node among various components, which include hardware devices, hardware control modules, and call control modules. FIG. 1 illustrates a schematic block diagram for this type of prior art gateway/gateway controller combination node 10.
The prior art combination node 10 includes a call control module 60 in electronic communication with a hardware control module 50. Several hardware devices 20, 30, and 40, such as voice trunks, announcement machines, switching modules, etc. are directly controlled by the hardware control module 50. In this prior art configuration, wherein the combination node 10 is typically embodied by a MSC, all of the information related to calls and their status is shared between the call control module 60 and the hardware control module 50 using internal software communication methods well known in the art.
Communications standards change rapidly. Newer standards may require separation of the control functions module 70 within a telecommunications node from the hardware functions module 80 within the node. Typical of such standards is the International Telecommunications Union Telecom Standards Sector (ITU-T) recommendation H.248 (incorporated herein by reference in its entirety), which defines the communications protocol used between elements of such a physically decomposed multimedia gateway. While simple communications between the control functions 70 and hardware functions 80 have been generally defined, methods and systems to handle specific events which occur during operation of the functional elements 70, 80 have not been addressed.
For example, assuming that the control functions module 70 is represented by a media gateway controller and the hardware functions module 80 is represented by a media gateway, as described in the ITU-T recommendation H.248, several operating scenarios arise which are not addressed by the protocol recommendation. These include circumstances surrounding a single call outage, a small restart operation, and a large restart operation.
The single call outage situation occurs when the hardware functions module 80 experiences a fault due to a particular call. The hardware functions module 80 typically acts to release the call, but fails to inform the control functions module 70 with regard to the call release activity.
Another event, often caused by software faults detected within the hardware functions module 80, is a small restart operation. This occurs when the hardware functions module 80 experiences a fault during the setup phase of a single call. The module 80 experiences the fault, but is unable to determine precisely which call (out of a plurality of calls handled by the module 80) is responsible for the fault. Therefore, all of the calls handled by the hardware functions module 80 (which are still in the setup phase) are released by the module 80.
Finally, another operation which may arise within the hardware functions module 80 is a large restart. This can occur when the hardware functions module 80 detects a fault related to one of a plurality of calls it is handling. However, the hardware functions module 80 is unable to determine precisely which call is responsible for the fault, and is also unable to determine which phase is operative (i.e., the setup phase or the through-connected phase) for the faulty call. While the control functions module 70 is informed of the fault, all of the calls must be released by the hardware functions module 80.
Thus, while a prior art combination node 10 is able to share information between the call control module 60 and the hardware control module 50, separating the node 10 into functional elements 70, 80, as required by various standards, leads to diminished ability to distinguish and efficiently handle various operational scenarios. More specifically, while there may be several levels of faulty behavior within the hardware functions module 80, only the most egregious (i.e., a large restart operation) is communicated from the hardware functions module 80 to the control functions module 70.
Therefore, what is needed is a system and method for managing a plurality of calls between separated functional elements, such as a first node (e.g., a control functions module, or a media gateway controller) and a second node (e.g., a hardware functions module, or a media gateway). Such a system and method should operate to record the existence of calls handled within the second node, and especially, to record an indication of whether each call has entered the through-connected phase. Further, call outage fault detection and small restart operations should be fully communicated to the first node by the second node as they arise. Such a system and method would allow the first and second nodes to operate with increased effectiveness.